[Field of the Invention]
The present invention relates to an illumination apparatus, an image sensor unit and an image reading apparatus.
[Description of the Related Art]
In general, an image sensor unit is used when reading an image of an original or the like. An image sensor unit emits linear light to an original or the like. In Patent Document 1, an image sensor unit is disclosed that emits light from a light source to an object of illumination from a light guide.
The image sensor unit of Patent Document 1 that is described above has a light guide cover that covers a light diffusing surface for the purpose of improving the utilization efficiency of light. The relative positional relationship between the light guide and the light guide cover is defined by engagement of a protrusion-like positioning portion of the light guide with an engagement portion of the light guide cover. However, since the engagement portion of the light guide cover is disposed close to the light source, a part of light that is incident on the light guide from the light source is reflected by the engagement portion and is emitted to the object of illumination. Therefore, there is a problem that the light amount emitted from the image sensor does not become uniform along the main-scan direction, and in particular the light amount on the light source side increases.    Patent Document 1: Japanese Laid-open Patent Publication No. 2014-33440